That’s fair, though I see his decision to kill the Courier as a necessary strategic one rather than a purely moral one. His plan to usurp House relied on the element of surprise, and leaving the Courier alive as a potential witness who could expose his plot wasn’t a feasible option. Personally I wouldn’t call it merciless, more just, “Sorry, but this is how it’s gotta be.”

“What I did to you was rotten, but if you think House, the NCR or Caesar won't kill to put Vegas in their pocket, I really did blow out your brains." _ Benny

Kill him and drag his body to the grave he buried me at

Let him blather for a while, then shoot him and take his sweet suit. My Courier might be a blood soaked drug addicted psychopath from hell, but they still know how to be fashionable.

Send him to his room then detonate the C4 in his room.

Have sex with him and kill him in his sleep afterwards

I have yet to meet a man who can outsmart mini nuke

Crucifixion.

Let him go at the tops, then fight him in the arena.

I “let him go” to open the hidden vault 21 tunnel connection in the Tops and then kill him, after exhausting all the dialogue I can.

It's funny to run through Cazador Canyon, get to the Strip, enter the Tops, take drugs, then start running around with a switchblade and slaughtering everyone in the casino.